Focus detector having first and second non-overlapping sensor series

Abstract

Disclosed is an optical system for detecting the state of focus in which the exit pupil of an image-forming optical system is optically divided into a plurality of exit pupils by an optical member having a beam splitting element, the image-forming light beams from the divided exit pupils are used to form a plurality of image intensity distributions regarding an object image, sensor series each having a plurality of sensors and putting out signals corresponding to the image intensity distributions are disposed at positions whereat the plurality of image intensity distributions are formed, and the output signals from the sensor series are used to detect the relative position of the image intensity distributions to thereby discriminate the state of focus of the image-forming optical system.

What we claim is: 
     
       1. An optical system for detecting the status of focus, comprising: an image-forming optical system;   a sensor portion disposed near a predetermined image plane of said image-forming optical system, said sensor portion having a first sensor series and a non-overlapping second sensor series, said first sensor series having a plurality of first sensor units, each of said first sensor units having a first lens portion and a first sensor, said first lens portion having a light-condensing characteristic at least in a predetermined one-dimensional direction, said first sensor being disposed at a first position to receive light from said first lens portion, said second sensor series having a plurality of second sensors units, each of said second sensor units having a second lens portion and a second sensor, said second lens portion having a light-condensing characteristic at least in said one-dimensional direction, said second sensor being disposed at a second position to receive light from said second lens portion; and   a beam splitting element disposed between said image-forming optical system and said predetermined image plane, said beam splitting element deflecting a light beam passed through said image-forming optical system in a plurality of directions and directing a first one of the deflected light beams to said first sensor series and a second one of the deflected light beams to said second sensor series;   whereby detection of the state of focus of said image-forming optical system is effected by the use of output signals from said first and second sensor series which correspond to the image intensity distributions regarding respective object images.   
     
     
       2. The optical system according to claim 1, wherein said first position of said first sensor is a position at which only a light beam passed through a first portion of the exit pupil of said image-forming optical system is incident after having passed through said first lens portion, and said second position of said second sensor is a position at which only the light beam passed through a second portion of the exit pupil of said image-forming optical system is incident after having passed through said second lens portion. 
     
     
       3. The optical system according to claim 2, wherein each said lens portion has a respective optical axis, and the first sensor for the first lens portion of each said first sensor unit and the second sensor for the second lens portion of each said second sensor unit are disposed in opposite directions on the opposite sides of the optical axes of said first and second lens portions. 
     
     
       4. The optical system according to claim 3, wherein the first lens portions of said plurality of first sensor units and the second lens portions of said plurality of second sensor units are disposed on the same plane, and the first sensors of said plurality of first sensor units and the second sensors of said plurality of second sensor units are disposed on the same plane. 
     
     
       5. The optical system according to claim 2, wherein a first field lens is disposed between said beam splitting element and said first sensor series, a second field lens is disposed between said beam splitting element and said second sensor series, said first field lens causes said first sensor to be imaged near the first portion of the exit pupil of said image-forming optical system through said first lens portion, and said second field lens causes said second sensor to be imaged near the second portion of the exit pupil of said image-forming optical system through said second lens portion. 
     
     
       6. The optical system according to claim 5, wherein said first and said second field lens are made integral with each other. 
     
     
       7. The optical system according to claim 1, wherein said beam splitting element is in the form of a one-dimensional microprism and deflects an incident light beam in two directions. 
     
     
       8. The optical system according to claim 1, wherein said beam splitting element is spaced from an image-forming plan of said image optical system.